Helping people with computers... one answer at a time.

Sharing sensitive documents over the internet is both common and commonly done wrong. I'll look at the pitfalls and alternatives.

I wished to send some personal documents to my lawyer via Google Docs for security reasons but my attorney refused, saying that she doesn't "do Google Docs." Instead, she prefers that I send her my files of a personal nature via email attachments. I object to this as being far less secure than Google; SMTP is inherently insecure, but HTTPS is very secure. Forget about setting up encrypted email. How do I convince said lawyer that my privacy interests are paramount to her convenience interests?

Well, I can't answer that last question: it's difficult to persuade people who are set in their ways, as it sounds like your attorney might be.

I'll discuss some of the pros and cons of the two approaches that you mention and throw out a few additional ideas of my own.

I just went through this with my bookkeeper, who is decidedly more open minded and security aware.

Plain Old Email Attachments

Unencrypted email is perhaps the most common and by far, the least secure way to get any document from point A to point B. Email, and the document, travel unencrypted between mail servers and reside in unencrypted form on those mail servers while they await transmission or download.

Put another way: anyone with access to the servers or the ability to snoop in on the transmissions to and from the servers could read your email and documents.

Worse, any kind of email hiccup, like a mistyped email address or a hacked email account, could end up delivering those unencrypted documents into the hands of the wrong person.

Now, on the flip side, with the possible exception of hacked accounts, all of these accidents that could happen don't happen very often at all. Unless there's someone specifically looking to intercept your email, it's unlikely that anyone will.

"Unencrypted email is perhaps the most common and by far, the least secure way to get any document from point A to point B."

Of course, communicating with an attorney would be one of those cases with a slightly higher than normal probability of someone actually being interested in doing just that.

Google Docs

Using Google Docs as a secure transmission medium is an interesting approach. You should be aware of a few possible issues:

  • You're placing sensitive information in the hands of a third party (Google), though admittedly, a third party whom you trust.

  • Google, having access to the documents, could be required to divulge them in response to a court order.

  • And, of course, if any account with access to the documents is hacked, the information can be exposed.

Encrypted Email

One approach that would work very well all around is natively encrypted email.

The problem is that the adoption of email encryption, including consistent support in major email programs, is nowhere near what it needs to be for this to work. On top of that, it's just not as simple to set up as it should be.

To be honest, I'm somewhat surprised that the legal profession as a whole hasn't been pushing harder for this solution to be more ubiquitously available.

This solution would be ideal because the documents would be encrypted before they leave your machine and would remain encrypted until they reach the destination machine. Simple account hacks or email interception would not allow someone to view their contents - they'd have to actually break in to one machine or the other and gain access to the encryption keys.

Manually Encrypted Attachments

Another approach might be to manually encrypt your documents before emailing them to your attorney. You two would then share a password separately from email that would be used to decrypt the documents.

Tools, such as the most popular "zip" utilities (including 7-Zip), will allow you to encrypt a collection of documents into a single archive. AxCrypt will allow you to encrypt a single file. Tools like TrueCrypt could be used, I suppose, to send a virtual drive container file, but that would be pretty cumbersome.

Zip files are fairly ubiquitous; having one ask for a password on open might not be too much of a stretch for the less technically inclined.

At least with a strong password, you can feel safe emailing it as an attachment.


This turns out to be a potentially interesting solution. While it does involve installing Dropbox on both machines and trusting a third party, this could be the easiest of all solutions with a very high level of security.

By default, folders that you set up in Dropbox are private, meaning only machines that are logged into your Dropbox account can see the folder and its contents. This is the typical approach to sharing files across multiple machines used by the same person.

You can specify that folders be public, visible to the entire world, at a Dropbox web address. But that's definitely not what we want here. Smile

Instead, you can specify that a folder be shared with another Dropbox user's account. That folder will then appear in both of your Dropbox folder trees.

Any documents that you place in that folder will be securely copied to the other person's machine, and vice versa.

In transit, the documents are protected with https connections and they are stored on the Dropbox servers in an encrypted form so that not even Dropbox employees can access the files. (More on dropbox security.)

If your attorney already is, or could be convinced to be, a Dropbox user, this could be a very easy and workable solution.

What I Did

I'm a geek. I have my own server protected with https connections and access control. I simply uploaded the files there (securely, of course) to a location to which I gave my bookkeeper sole access.

Had that not worked, I would have suggested Dropbox.

If that hadn't been acceptable for whatever reason, I would have use encrypted attachments using 7-Zip.

And had that not worked, and no appropriate alternative had been suggested ... well, I guess I would have found another bookkeeper that more appropriately understood digital data security.

Article C4785 - April 6, 2011 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Adam Pomson
April 7, 2011 5:01 AM

all the negatives you stated for Google Docs are also true for DropBox!
AND you have missed out a key point
Google slice and dice all docs so that even someone standing next to a google server with the hard drive in their hand will have nothing more than small unreadable part of a doc
someone getting your username and password is the only real threat
but that threat is much much smaller than say someone stealing your laptop etc

Actually as I understand it, documents stored in Google Docs may not be encrypted, and thus potentially accessible to Google employees - either maliciously (unlikely) or in response to legal action. Dropbox files are encrypted such that not even a Dropbox employee has access to the contents. Naturally ALL sharing mechanisms that rely on only a username & password are vulnerable to account theft. Regardless of where you store your files you do need to take appropriate steps to secure those accounts. I'd feel comfortable sharing more via DropBox than I would via Google Docs, but as others have pointed out the ultimate would be to encrypt with another tool before sharing.

April 7, 2011 5:44 AM

dear leo,
just like 2 fax modem fitted laptops can send and recieve fax over a telephone line (i have tried it); is there a way to share email or e-documents? (i read something about it or related something quite a while ago) i think that would be more secure way to transfer a file as the connection will not be with the web but between 2 pc's. pls write an article on it. thanx

April 7, 2011 2:43 PM

Many businesses are clueless about email security. I couldn't believe it when a loan agent told me he sends all the sensitive financial documents to mortgage bank via plain email. When I explained that it was totally unsecure, he was really surprised (I'm not sure he even understood).

It's no wonder that faxes are still the de facto standard for transmitting business data.

Mark J
April 8, 2011 12:15 AM

@Bucky: Faxes can be almost as insecure as open email if anyone is tapping your phone line. The advantage of a fax is that it doesn't reside on someone else's server for ever.

April 8, 2011 3:49 PM

@Mark: Yes, but from what I understand, it is difficult to tap a phone line. And like you said, a fax is a one time transmission.

Whereas it is much easier to "tap" someone's email. You can easily sniff network packets. And anytime that person checks their email, they could re-expose the sensitive documents. Or the person could get phished, giving hackers access to EVERYTHING in their account. Especially these days with the philosophy of "don't delete anything, leave everything on the cloud".

April 12, 2011 8:19 AM

What about the sneakernet? Id trust that more....

April 12, 2011 9:49 AM

I use Enigmail, an OpenPGP encryption extension for Thunderbird; works well for basic mail and isn't terribly hard to set up. There's also a 3rd-party free encrypted e-mail service -- Hushmail -- that's very easy to use, but if you fail to use it at least once a month your account disappears. Clever way for them to get you to use their paid service, which is reasonable. Biggest problem with any encryption approach is that both ends of the link have to participate. I wouldn't be surprised to see a comprehensive solution for the major e-mail clients in the marketplace soon, although the government will probably discourage its use.

April 12, 2011 9:50 AM

I'm surprised it wasn't mentioned, but you could always burn to a disk and mail it.

Tom R.
April 12, 2011 11:23 AM

Keith - I'm the original questioner for this topic. If I was going to use snailmail I would have just sent the attorney the paper documents ;-) As it was, there was a time constraint involved that precluded US mail. My sister was acting as a family advisor to me on this matter and sniffed when I told her I didn't care for the idea of sending confidential info over plain email. "That's the way business is done these days."

Like Leo said, people can be very set in their ways and are often very reluctant to change their ideas about new realities.

Cindy Gioffredi
April 12, 2011 12:21 PM

I use a very simple method. I will protect a document from being opened by adding a password before sending it to the receiver. The receiver gets a call from me with the password he or she needs to open the file. Archaic method I know, but I also have a pet dinosaur . . .

You need to be careful "adding a password" - not all programs do so properly and many are often easily hacked or bypassed. Better to use a Zip file or something like AxCrypt in the same manner (encrypt and then call in the password you used).

April 12, 2011 2:01 PM

Massachusets law (201CMR17) requires (since March 1, 2010) businesses of all kinds to encrypt messages or attachments when they send "personal" information by e.mail!

I personally either use Dropbox or attach an encrypted PDF and forward the password by another method (phone call, fax, or e.mail from a different account).

I'm also involved in a closed beta of a new service called Ziptr that is very promising! Look for a public beta soon at (i hope this doesn't count as spam. If so, I apologize!).


April 12, 2011 3:58 PM

I believe that DropBox can be used via a web interface, so the attorney wouldn't even have to install the software.

April 12, 2011 4:59 PM

To Cindy. Passwords on documents are only a very basic form of protection. I can break one for any Microsoft file in a minute. Google for solutions and you'll be shocked at how weak security at that level is. Same with passwords for logins - Linux will walk in the front door without even knocking.

April 12, 2011 7:58 PM

After reading your article in the morning, I came across this one in the evening. Talk about good timing.

Dropbox: Insecure by Design?

Short form, dropbox encryption depends on a static hash value saved on the user's HD. Bad guys can find and use the hash to hack dropbox.

Fascinating article. While I agree with Dropbox's response that "for the attack to work, a hacker would have to gain access to a user's computer. At that point 'the security battle is already lost,' they say, because the hacker would have access to every file on the computer.", which does at least limit the scope of the problem, the recovery scenarios as described are troubling. Thanks for the link.

Cindy Gioffredi
April 13, 2011 8:03 AM

As for password protecting documents, that's something I use not when personal info is an issue; rather when I want to pass on a "Not so Smart User" story (& I have a MILLION of them as you can well imagine!) & would rather the subject of the story not be outed. Example: I had a guy page me in a panic ready to jump from the window cuz his PC was broken! It would not power up. END OF THE WORLD!!!!! I went to his office - hit his light switch - no power in his office at all - nor the office next to his. Fuse had been blown & I simply reset the breaker switch. & you are absolutely right about Linux being unstoppable when it comes to cutting thru a password. A very handy tool to have around! :-) Cindy

Richard J.
April 19, 2011 12:34 PM

The most secure way of sending documents is by FAX. Being in the cryptology department for 20 years in the Navy and still working for the government, Fax machines are still the most secure way of sending documents. You call the person or office you are sending it to, let them know you are sending those documents "now" and to call you when they are received, or in some cases you can stay on the line.

I'm sure your attorney has a Fax machine.

June 5, 2011 9:00 PM

I know Leo likes Dropbox, but it appears Dropbox has been lying...from a recent NYT article..

"A security expert did recently complain to the Federal Trade Commission about how Dropbox encrypted files on its service. Dropbox’s employees could get access to unencrypted files, he said, and he accused the company of failing to disclose this."

Tom Veil
March 22, 2012 3:09 PM

If you want to be *really* paranoid, you can create a TrueCrypt volume within DropBox, share the volume with someone else who also has a DropBox account, and give them the password. Do a Google search for "Dropbox Truecrypt" and you'll find lots of articles on how to do this. I do this with my accountant when sending tax records with SSN numbers.


February 4, 2013 6:22 AM

Doesn't AxCrypt require the receiver of the email to not only have a pass phrase but ALSO have AxCrypt installed? I think I could persuade the bank officer I'm trying to send secure info to, to use a pass phrase but not install AxCrypt.

Mark J
February 4, 2013 10:55 AM

Programs like AxCrypt, 7Zip and many other encryption programs allow you to create self decrypting files. These are .exe versions of the encrypted files which when run, prompt you for the password and decrypt themselves.

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